Calibration of focal plane arrays in image detection systems is necessary to adequately detect images within a scene. Typical opto-mechanical calibration techniques include using a shutter to flash in front of the focal plane array during calibration. The shutter may include a specific reference image such that the focal plane array detects a specific reference in order to calibrate its image sensing devices. The shutter may include a flat mirror such that the focal plane array detects itself for calibration purposes. The shutter/flat mirror technique only allows the focal plane array to calibrate on itself or a specific reference. Therefore, imaging system can benefit from improved opto-mechanical calibration schemes.